Would you castrate yourself to prevent unwanted pregnancy?

As in cut your testicles off? I was thinking that if you had already gotten past puberty, and assuming that you could still get an erection, could then cut it off to get rid of both an overload of sperm cells and testosterone (having less testosterone would=less rage, less body hair (if you do it early enough anyway), and more hair on top of your head). Am I right? If not, then why can't you get an erection/enjoy S3X after the castration?